It is common practice to chlorinate large bodies of water. Examples are the sanitizing of swimming pools, spas, the treatment of small water supplies or sewage systems, the prevention of algae growth in cooling towers, etc. to combat the occurrence and growth of micro-organisms. There are a number of problems encountered by the addition of quantities of chlorine or chlorine-containing compounds to a body of water at regular intervals in order to maintain the required chlorine concentration. Typical liquid chlorine systems suffer from the caustic and volatile nature of the chlorine in its liquid state. The shipping and handling of this liquid chlorine is both dangerous and expensive. One solution to these problems is the use of electrolysis to chlorinate the water. Electrolysis requires salinating the water to between 0.2% and 0.8% by weight of sodium chloride and then passing the salinated water through an electrolytic cell that has spaced electrodes coupled to a source of d.c. voltage. In most of these applications, the pH of the water being treated must be kept within narrow limits, for example 7.5.+−.0.1 pH units.
The current flowing between the electrodes forms a hypochlorite solution which has the effect of killing off and preventing the growth of micro-organisms. There are many types and forms of electrolytic cells that may be used in the chlorination of pools and spas and water supplies. Some are positioned in the plumbing associated with the filtration plant of a pool, while others are suspended or immersed directly into a body of water.
For domestic swimming pools and spas, the electrolytic cell usually runs at a d.c. voltage of between 18 to 26 volts, enabling a current of between 4 to 6 amps to flow between the electrodes of the cell. The supply of the d.c. voltage is usually from a power pack that would include a step down transformer and a rectifier to step down the a.c. mains voltage to the d.c. voltage of between 18 and 26 volts.
One problem with electrolytic chlorination systems and other systems is that, due to the addition of fresh water through rain, leaks, or other means the salt level is reduced. This requires the addition of salt into the body of water to be sanitized. In the electrolytic chlorinator system, the salt is important to both the maintenance of the water and to the maintenance of the equipment. Too little will not allow sufficient chlorine to be produced and too much salt can damage the pool equipment.
Typically, the salt chlorine generators sanitize the pool on a daily basis. Thus most electrolytic chlorine systems have the ability to check the salinity level of the pool and will indicate to the user when the system requires additional salt. Even if the salt condition is not brought to the immediate attention of the user, to regain the desired salinity can require the addition of large quantities of the salt composition. However, the alerts from these types of systems often go unattended by the typical end user, resulting in an even greater salt imbalance. Generally, a minimum of 1 to 2 bags can be required, especially after a heavy rain. These bags are typically bought at pool supply stores and weigh 40 to 80 pounds each. This can be an inconvenience, especially for the older end user, and is still a difficult task for the general end user.
Thus a need exists for a system that would automate and reduce the possibility of large scale salt imbalances in electrolytic chlorinator systems by providing a convenient and efficient manner for adding salts to water for chlorination. Such a system would automate the salt dispensing into the pool or body of water and keep the salinity levels at optimum operating levels for the electrolytic cell chlorinator. This would help keep algae growth down and extend the life of the typical electrolytic cell.